The present invention pertains to a modular sewing machine having a frame construction adapted to support the various driving elements of the machine which are necessary to actuate the stitching instrumentalities and the workpiece transport or feed dog mechanism during operation of the machine.
As is well known to those conversant in the sewing art, sewing machines are commonly identified by the particular type of stitch they are adapted to form such as straight stitches, zig-zag and overlock stitches, etc., or by the different seaming operations they are capable of accomplishing.
Additionally, it is common practice to identify sewing machines according to their type of base which may be of the conventional planar type or free arm type, etc., and signifies to those familiar with such machines the particular type of sewing operation they are capable of performing.
With industrial type sewing machines utilized for producing articles of wearing apparel, a significant problem exists relative to the versatility of such machines for generally each specific sewing operation requires one particular and well defined type of machine.
To try and correct this problem, attempts have been made to unify and simplify a number of the driving elements of the sewing machines in order to facilitate their assembly within the frame thereof.
To accomplish this, the driving elements for actuating the needle, those for effecting advance of a workpiece during seaming as well as those for the operation of the machine itself, were provided with independent supporting members which provided a means whereby the separate devices could be easily inserted and removed en bloc from within the machine's frame. Another approach was directed toward providing a simplified frame structure for sewing machines; however, this approach had its limitations for it could only be effective on machines that did not differ from one another by an appreciable amount.
In the so called "column" sewing machines in which the latter defines the usual working surface and as is well known, can have its distance from the machine's upright adjusted, it is possible to obtain a greater throat distance for the needle by inserting a spacing insert member intermediate the latter and the upright as well as by effecting movement of the column away from said upright.
A further approach well known in the art pertains to the frame that was subdivided into several interchangeable parts which are fitted together prior to complete assembly of the machine.
More precisely, this frame includes a base, an upright provided with an arm that is divided longitudinally into two parts with a first part thereof being adapted to receive the needle-carrying head and which can be assembled to the base disposed beneath it. The second part of the arm forming a cover is adapted to assemble to the first part.
From the above description of the prior art devices for converting sewing machines from one type to another, it should be readily understood that such changes require the expertise of those knowledgable in the building and repair of machines, and cannot normally be accomplished by the operators themselves. Because of this, the problem of being able to quickly and easily change a sewing machine so that it will form a different type of stitch or accommodate a different sewing operation has not been resolved.
An object of the present invention is to provide a modular type sewing machine in which its interchangeable devices can be accomplished in a minimum amount of time, and which does not require the skill of a trained technician.